Research suggests that people with schizophrenia or SAD have identifiable early warning signs that signal the onset of a relapse. Accordingly, the Program for Relapse Prevention (PRP), which has been shown to prevent relapse and hospitalization, calls for monitoring for signs of relapse with prompt clinical intervention, when indicated, alongside maintenance pharmacotherapy. The Assertive Community Treatment (ACT) program incorporates the PRP approach as a part of its management of people with serious mental illness (SMI). Text messaging is a widely used technology that provides opportunities to implement a PRP-based program in a cost-effective manner. Nationally, up to 81.4% of people with SMI report owning a cellphone, and text messaging has been reported as the second most common use of their phones. We are therefore optimistic about its feasibility to deliver a cost-effective program that empowers patients to manage their symptoms, while also increasing the patient-provider communication flow if warning signs worsen, with improved mental health services outcomes as a result. In response to RFA MH-16-410, we propose to develop and test an innovative service delivery program, Texting for Relapse Prevention (T4RP). We base T4RP components on key ACT components. Specifically, the program will improve care outcomes by: (a) promoting ongoing monitoring of participants' early warning signs to quickly identify possible relapse; (b) promoting medication adherence; (c) empowering patients to identify and manage early warning signs of relapse; and (d) improving communication between patients and providers to collaboratively develop a comprehensive plan to treat symptoms, if self-management techniques are insufficient. Specifically, we aim to: Specific Aim 1: Design T4RP, a comprehensive relapse prevention program delivered via text messaging, with the ongoing feedback of people diagnosed with schizophrenia or SAD and their providers. To ensure that the program is usable by patients and providers alike, we will conduct facilitated interviews with patients (n = 20) and providers and administrators (n = 12). Text message content will then be developed with the ongoing participation of people with schizophrenia/SAD and providers in our Content Advisory Team (CAT; n = 15: 10 patients and 5 providers). Specific Aim 2: Test program feasibility, safety, and acceptability over a 6-month period in a pilot study with people who have schizophrenia or SAD (n = 40) and their mental health providers. Participants will be randomly assigned to either the intervention or a treatment as usual (TAU) control group. Subaim 1: Identify participant characteristics and experiences that affect program feasibility and acceptability. Subaim 2: Identify provider characteristics and experiences that affect program feasibility and acceptability. Specific Aim 3: Assess the program's impact on patient outcomes and target mechanisms.